Image forming apparatuses are devised to form an image on a printing medium, e.g., sheets of paper, according to input image signals. Examples of image forming apparatuses include printers, copiers, facsimiles, and so-called multi-functional devices that combine some of the functionalities of the aforementioned devices.
Such an image forming apparatus generally includes, e.g., a body defining the overall external appearance of the apparatus, a printing medium supply unit in which sheets of printing media are stored, a developing unit for forming a developer image on a printing medium supplied from the printing medium supply unit, a fusing unit for fusing the developer image to the printing medium and a discharge unit for discharging the printing medium bearing the fused image to the outside of the body.
With the above-described configuration, after the formation of an electrostatic latent image on the surface of a photosensitive body by irradiating light on the charged surface of the photosensitive body of the developing unit, developer is fed to the electrostatic latent image formed on the photosensitive body, to thereby develop the electrostatic latent image into a visible image. Subsequently, the visible image formed on the photosensitive body is transferred to the printing medium supplied from the printing medium supply unit. As the printing medium passes through the fusing unit, the image transferred to the printing medium is fused to the printing medium, thus completing the image formation on the printing medium. The printing medium, on which the image is formed as described above, is discharged to the outside of the body by a discharge unit of the image forming apparatus.
The developing unit may itself include a housing that defines the overall external appearance of the developing unit, and a number of components accommodated in the housing. Such components may include the above-mentioned photosensitive body and a developing body for supplying the developer to the photosensitive body so as to form the visible developer image on the photosensitive body. The housing includes a first frame that defines a developer storage compartment for storing developer therein and a developing compartment in which the above mentioned components, e.g., the photosensitive body and developing body may be received. The housing may also include another frame defining a waste toner storage compartment for storing therein waste toner.
In a developing unit of the above-described configuration, the first frame further defines a partition between the developer storage compartment and the developing compartment. The partition has a developer supply opening through which the developer from the developer storage compartment is supplied into the developing compartment. In order to prevent the developer stored in the developer storage compartment from leaking through a gap between the photosensitive body and the first frame during storage and/or transporting of the developing unit, the developing unit is provided with a removal member is detachably attached to cover and thus to close the developer supply opening . At the time when it is desired to put the developing unit into use, the removal member is detached to open the developer supply opening, thus allowing the developer to be supplied to the photosensitive body.
Unfortunately, the installation of the removal member during the manufacture of the developing unit is difficult to accomplish because the access to the developer supply opening in the first frame of the developing unit may be obstructed at least partially by the various components arranged in the developing compartment or in some cases by the developing compartment itself. Thus, a configuration of developing unit that allows a simpler installation of the removal member is desirable.